48 



THREE CRUISES OF THE "BLAKE." 



will serve as an example. In this species the filaments of each 

 antenna are greatly elongated, - - fully once and a half the 

 length of the body ; the legs increase in length towards the 

 posterior extremity, and the three anterior pairs have minute 

 claws ; the dactyli of the two posterior pairs, nearly twice as 

 long as the preceding pair, are exceedingly weak and slen- 

 der, and are evidently tactile rather than ambulatory organs, 

 modifications which seem adapted to the deep-sea life of 

 these animals. We are constantly struck with the exquisite 

 delicacy and great diversity of the organs of vision, of hear- 

 ing, of touch, and even of smell, in the deep-water crustaceans. 

 The antenna? and claws are frequently of excessive length, as 

 if to facilitate exploration of the ooze and the sounding of 

 objects. 



We find in deep water huge schizopods, Gnathophausia (Fig. 

 249), of a beautiful red color. The majority of schizopods pre- 

 viously known were mainly pelagic, and belong to a group of 

 small crustaceans which have the thoracic feet all alike, divided 

 into two branches and sometimes carrying free gills. Some of 

 these deep-water schizopods are provided with special organs 



of phosphorescence, such 

 as luminous plates behind 

 the eyes or over the legs. 

 Among the various groups 

 of crustaceans some have 

 phosphorescent eyes, while 

 in others the phosphores- 

 cence is diffused, or limited 

 to special parts of the body 

 at the time of breeding, or 

 when irritated. 



Among the Atlantic spe- 

 cies of isopods, we may fig- 

 ure the bright orange Sysce- 

 nus (S. infelix, Fig. 250), which is found at a depth of nearly 

 400 fathoms, and Rocinela (R. oculata, Fig. 251), the upper 

 surface of the head of which is nearly covered with large ocelli 

 arranged in rows. From the collection made in the West Indian 



Fig. 250. Syacenus in- 

 felix. About ij & . 

 ( Harger. ) 



Fig. 251. Roci- 

 nela oculata. ^. 

 (Harger.) 



